Change closing parenthesis style for Solidity

[loredanacirstea]

As mentioned here #39 (comment)
and changed here raiden-network/raiden#1380,

this is the style that should be used:

    function recoverAddressFromSignature(
        uint64 nonce,
        uint256 transferred_amount,
        bytes32 locksroot,
        bytes32 extra_hash,
        bytes signature
    )
        constant
        internal
        returns (address)
    {
        ...